A 5.2 GHz 47 dB image rejection double quadrature Gilbert downconverter using 0.35 mu m SiGe HBT technology

Abstract

A 5.2 GHz 1 dB conversion gain, IP(1dB) = - 19 dBm and IIP(3)= -9dBm double quadrature Gilbert downconversion mixer with polyphase filters is demonstrated by using 0.35 mu m SiGe HBT technology. The image rejection ratio is better than 47 dB when LO=5.17 GHz and IF is in the range of 15 MHz to 45 MHz. The Gilbert downconverter has four-stage RC-CR IF polyphase filters for the image rejection. Polyphase filters are also used to generate LO and RF quadrature signals around 5 GHz in the double quadrature downconverter.